Switch.



W. L. HAMILTON.

SWITCH.

APPLICATION FILED MAR. 13. 1915.

1,230,089. Patented June 12, 191?.

WITNESSES: 11v VENTOR.

ATTORNEY.

UNITED STATES PATENT OFFICE.

WALTER L. HAMILTON, 0F HOLYOKE, MASSACHTISETTS, ASSIGNOR TO HENRY G.AVERY, 0F HOL'YOKE, MASSACHUSETTS.

SWITCH.

Application filed March 13, 1915. Serial No. 14,109..

To all whom it may concern:

Be it known that I, WALTER L. HAMILToN,

a citizen of the United States of America,

residing in the city of Holyoke, county of Hampden, and Commonwealth ofMassachusetts, have invented certain new and useful Improvements inSwitches, of which the following is a specification. v

Thisinvention relates to circuit closers and particularly to improvedcircuit closers, which are arranged to be operated by sudden changes intemperature.

An object of the invention is to provide an improved circuit closer,operable by sudden changes in temperature, which is extremely sensitiveand is arranged to respond to small temperature variations.

Another object is to provide 'an improved device of the class described,which, although operable by sudden changes, is unaffected by gradualvariations in temperature.

Another object is to provide an improved device of the class described,which may be readily converted from a circuit closer to a circuit openerto open a circuit upon sudden changes in temperature.

A further object is to provide an improved circuit closer or opener,which is simple and comparatively inexpensive to manufacture.

With these objects in view, the apparatus in general comprises a contactarm pivotally supported in a delicate manner on suitable knife edges, apost with which said arm is arranged to contact to close an electricalcircuit, and a wire passing around a portion of the knife edge supportand having its two ends fixed to the base plate of the apparatus. Thiswire is arranged substantially in V- form having its two ends secured tothe base plate in spaced relation with its central portion extendingabout the lmife edge support. Thus, the wire, as arranged, has twosections and theapparatus is constructed and arranged so that the wirewill turn the contact arm and close a circuit, whenever a difference inthe rate of expansion of the two sections of the wire occurs.

One preferred embodiment of my invention, for the purposes ofillustrating the way in which the invention may be carried out, is shownin the accompanying drawings, in which- I Figure 1 is a top plan view ofthe apparams;

Fig. 2 is an end elevational view thereof;

Fig. 3 is a sectional elevational view taken I on the line 33 of Fig. 1and looking in the direction of the arrows;

Fig. dis a sectional plan view of a portion of the apparatus andillustrates the pivotal mounting for the contact arm;

Fig. 5 is a sectional elevational view of the portion of the apparatusshown in Fig. 4;

Fig. 6 is a perspective view of the knife edge member in which thecontact arm is mounted; and

Fig. 7 is a view similar to Fig. 1 showing the apparatus arranged forclosed circuit operation.

Referring to the drawings, 1 represents a baseplate, suitably formed toreceive the various parts ofthe apparatus and preferably hollowed out,as shown in Fig. 3, to receive the terminal screws. Secured to the underside of the base 1 and within the hollowed out portion, is a flat spring2 which has a vertically bent end portion 2. The latter extends upwardlythrough a suitable opening in the base 1, as shown in Fig. 3,

and has an opening 3 therein. This opening is formed by first punching ahole through the flat metal and then swaging this hole, by means of adie, until the metal adjacent the hole is forced away from the plane ofthe flat metal spring 21 By this operation, a rounded flaring opening isformed as will be seen in Figs. 4: and 5. V

In the rim 4: of the opening'3 are a pair of notches arranged verticallyone above the other to receive a pair of knife edges 6. The latter areclearly shown in perspective in Fig. 6 and are formed by filing orcutting away the end portions of a short cylindrical piece 5. within theopening 3 (see Figs. 4 and 5) and has secured thereto an arm 7 Passingcentrally around a portion of the periphery of the member 5 is a wire 8,which is arany suitable material but preferably ma- This cylindricalportion 5 lies terial having a high de es of elasticity and a relativelyhigh coe cient of expansion should be-employed. The two ends of thiswire are brought backwardly through the opening 3 and secured undertension to a pair of spaced posts 9 integral with the base 1'. One ofthe two sections of the wire 8 extending from the posts 9 to the member5,-the uppermost as viewed in Fig. 1, has a tube 10 thereon. The latterrests loosely upon the wire 8 and is formed of suitable heat-resistingmaterial, such as pipe clay, for example.

Secured to the base 1 by the screw 1 1 and suitably insulated therefrom,as shown in Fig. 3, is a post 11. A screw 12 extends horizontallythrough the post 11 and is provided at its end with a contact tip ofsuitable material, such as platinum, for ex ample. This screw 12 may beclamped in various positions of adjustment by a set screw 16 verticallymounted in the post 11.

'The arm 7, heretofore described, is arranged,

when moved, to engage the screw 12 and thereby close an electricalcircuit. The terminals of this circuit are connected to the apparatus bythe screws 13 and 14:, the current bein transmitted from the screw 13 tothe arm by the metallic base 1, spring 2, and member 5.

If desired, a covering 15, formed from crossed wires bent as shown inFig. 2, may

be secured to the base 1, as shown in Figs. 1-

and 2 to protect the apparatus from damage without interfering with thetransmission of heat waves to the wire 8.

The wire 8 and arm 7 are so assembled that the latter does not touch thescrew 12.

It will be seen that one section of the wire equally with the uncoveredsection, in other words the expansion of covered section of wire 8 isretarded unless the rise in temperature is gradual. It will therefore beseen that, with unequal expansion of the sections of wire 8, there willbe an unbalanced pull on the covered section of the wire which will turnthe member 5' on its knife edges and the arm 7 will be turned in thedirection of the arrow to engage the screw 12. Thus, an electricalcircuit including any desired alarm devices or other electricallycontrolled devices may be closed by a sudden rise in temperature. It isto be understood that wire 8 has sufiicient elasticity to permit it tobe assembled under an initial tension, which is great enough to preventslackening of the wire (and thus breaking the-grip of the wire on member5) as the total length if the wire increases under the action of eat. c

Gradual temperature changes do not cause the arm 7 to move. This is dueto the fact that there is time for'the heat to penetrate within theloosely fitting tube 10 to the wire. Thus, both sections are acted uponequally for all practical purposes by gradual changes and no appreciableturning movement results.

The apparatus has been described as arranged for open circuit operation.It may, however, be easily arranged for closed circuit operation bysimply placing the tube 10 on the other section of the wire 8 as shownin Fig. 7

It is to be noted that the apparatus is extremely simplein construction,having few parts, each of which is simple to make. .No specialoperations requiring skilled labor are necessary, and the device may bemade up at a comparatively low cost. However, notwithstanding thesimplicity of the structure, it is extremely delicate and is sensitiveto very small sudden changes in temperature.

It is recognized that many changes may be made in the specific form ofthe apparatus described without departing from the scope of myinvention, which is defined in the appended claims.

What I claim is:

1. A circuit closer, comprising, in combination, a suitable base, amovable contact arm pivotally mounted thereon and forming one terminalof an electrical circuit to be closed, a fixed contact on said base andinsulated therefrom, said contact arranged in the path of said arm andformin the other terminal of the circuit to be c osed, a wire arrangedin V-form having its two ends secured to said base and its centralportion in engagement with a portion of said movable arm, and a heatresisting element on a portion of said wire, all constructed andarranged so that a sudden change in temperature will expand certainportions of said wire more rapidly than other portions, whereby amovement of the wire results to turn said arm to engage said fixedcontact.

2. A circuit closer, comprising, in combination, a suitable base, amovable contact arm, arranged to form one terminal of an electricalcircuit to be closed, a knife edge support for said arm, a fixed contacton said base and insulated therefrom, said contact arranged in the pathof said arm and forming the other terminal of the circuit to be closed,a wire having its central portion in engagement with a portion of saidarm and its two ends secured to said base in spaced relation, and a heatinsulating tube surrounding a portion of said wire, all constructed andarranged so that unequal expansion is caused in certain portions of saidwire, whereby a movement of the wire is caused to turn said arm intoengagement with said fixed contact.

3. A circuit closer, comprising, in combination, a suitable base, ayieldable upright secured thereto, a movable arm adapted to r,aso,ose

form one terminal of a circuit to be closed, a member secured to saidarm having knife edges to engage said upright, a Wire bent into V-formhaving its central portion in engagement with said member and its twoends fixed in spaced relation to said base, a tube of heat resistingmaterial on one limb of said V-shaped Wire, and a fixed contact arrangedon said base in the path of said arm, said fixed contact being insulatedfrom said base and adapted to form the other terminal of the circuit tobe closed, all constructed and arranged so that one limb of saidl-shaped Wire is expanded by a sudden rise in temperature more rapidlythan the other limb, whereby a movement of the Wire is caused to turnsaid arm to engage said fixed contact and close the circuit.

4. A circuit controller, comprising, in combination, a suitable base, amovable contact arm pivotally mounted thereon and forming one terminalof an electrical circuit to be controlled, a fixed contact on said basearranged in the path of said arm and forming the other terminal of saidcircuit, a Wire arranged in if-form having its two ends secured to said.base and its central portion in engagement With a portion of saidmovable arm, and a heat resisting element .on a portion of said Wire,all constructed and arranged so that a sudden change in temperature Willexpand certain portions of said Wire more rapidly than other portions,whereby a movement of the Wire results to turn said arm relatively tosaid'contact to control said electrical circuit.

' WALTER L. HAMILTON.

Witnesses:

SAMUEL N. SENNA, GUSTAV BEYER.

